page_title: Stellar evolution
section_title: Massive stars
hierarchical_section_title: Stellar evolution / Mature stars / Massive stars
caption_attribution_description: English: Using ESO’s Very Large Telescope Interferometer astronomers have constructed this remarkable image of the red supergiant star Antares. This is the most detailed image ever of this object, or any other star apart from the Sun.
context_page_description: Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.
  Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase.
context_section_description: In massive stars, the core is already large enough at the onset of the hydrogen burning shell that helium ignition will occur before electron degeneracy pressure has a chance to become prevalent. Thus, when these stars expand and cool, they do not brighten as dramatically as lower-mass stars; however, they were more luminous on the main sequence and they evolve to highly luminous supergiants.  Their cores become massive enough that they cannot support themselves by electron degeneracy and will eventually collapse to produce a neutron star or black hole.
caption: Reconstructed image of Antares, a red supergiant
exif: {"Image ImageDescription": "Using ESO\u2019s Very Large Telescope Interferometer astronomers have constructed this remarkable image of the red supergiant star Antares. This is the most detailed image ever of this object, or any other star apart from the Sun."}